This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Currently there are limited treatment options for patients with pathological vestibular function. Loss of vestibular sensation from the inner ear results in imbalance and oscillopsia. Partial loss results in disequilibrium. Fluctuating loss in conditions such as Meniere's disease, results in intermittent vertigo and nausea. Our project was to develop an implantable vestibular prosthesis to replace lost vestibular function or correct abnormal vestibular function in patients suffering from these conditions. Specifically, we developed a modification of cochlear implant technology to provide the implantable portion of our device, and then developed new software and external hardware to drive individual semicircular canal nerves with electrical stimuli appropriate to produce reflexive eye movement responses in rhesus monkeys. We then recorded from individual vestibular neurons to determine the central processing that takes place during stimulation to produce the observed behavior. We are now using transtympanic injections of gentamicin to eliminate vestibular input and then using electrical stimulation to compensate for the loss.